/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.util;

import java.util.*;

/**
 * This StringParser can create StringMatcher instances for regular expressions matching names. The regular expressions
 * are interpreted as comma-separated lists of names, optionally prefixed with '!' negators. If a name with a negator
 * matches, a negative match is returned, without considering any subsequent entries in the list. The regular
 * expressions can contain the following wildcards: '?' for a single character, '*' for any number of characters, and
 * '<n>' for a reference to an earlier wildcard (n = 1, 2, ...)
 *
 * @author Eric Lafortune
 */
public class NameParser implements StringParser {
    private List variableStringMatchers;

    /**
     * Creates a new NameParser.
     */
    public NameParser() {
        this(null);
    }

    /**
     * Creates a new NameParser that supports references to earlier wildcards.
     *
     * @param variableStringMatchers an optional mutable list of VariableStringMatcher instances that match the
     *        wildcards.
     */
    public NameParser(List variableStringMatchers) {
        this.variableStringMatchers = variableStringMatchers;
    }

    // Implementations for StringParser.

    public StringMatcher parse(String regularExpression) {
        int index;
        StringMatcher nextMatcher = new EmptyStringMatcher();

        // Look for wildcards.
        for (index = 0; index < regularExpression.length(); index++) {
            int wildCardIndex;

            // Is there a '*' wildcard?
            if (regularExpression.charAt(index) == '*') {
                SettableMatcher settableMatcher = new SettableMatcher();

                // Create a matcher for the wildcard.
                nextMatcher = rememberVariableStringMatcher(
                    new VariableStringMatcher(null, null, 0, Integer.MAX_VALUE, settableMatcher));

                // Recursively create a matcher for the rest of the string.
                settableMatcher.setMatcher(parse(regularExpression.substring(index + 1)));
                break;
            }

            // Is there a '?' wildcard?
            else if (regularExpression.charAt(index) == '?') {
                SettableMatcher settableMatcher = new SettableMatcher();

                // Create a matcher for the wildcard.
                nextMatcher =
                    rememberVariableStringMatcher(new VariableStringMatcher(null, null, 1, 1, settableMatcher));

                // Recursively create a matcher for the rest of the string.
                settableMatcher.setMatcher(parse(regularExpression.substring(index + 1)));
                break;
            }

            // Is there a '<n>' wildcard?
            else if ((wildCardIndex = wildCardIndex(regularExpression, index)) > 0) {
                // Find the index of the closing bracket again.
                int closingIndex = regularExpression.indexOf('>', index + 1);

                // Retrieve the specified variable string matcher and
                // recursively create a matcher for the rest of the string.
                nextMatcher = new MatchedStringMatcher(retrieveVariableStringMatcher(wildCardIndex - 1),
                    parse(regularExpression.substring(closingIndex + 1)));
                break;
            }
        }

        // Return a matcher for the fixed first part of the regular expression,
        // if any, and the remainder.
        return index != 0 ? (StringMatcher)new FixedStringMatcher(regularExpression.substring(0, index), nextMatcher)
            : (StringMatcher)nextMatcher;
    }

    // Small utility methods.

    /**
     * Parses a reference to a wildcard at the given index, if any. Returns the 1-based index, or 0 otherwise.
     */
    private int wildCardIndex(String string, int index) throws IllegalArgumentException {
        if (variableStringMatchers == null || string.charAt(index) != '<') {
            return 0;
        }

        int closingBracketIndex = string.indexOf('>', index);
        if (closingBracketIndex < 0) {
            throw new IllegalArgumentException("Missing closing angular bracket");
        }

        String argumentBetweenBrackets = string.substring(index + 1, closingBracketIndex);

        try {
            int wildcardIndex = Integer.parseInt(argumentBetweenBrackets);
            if (wildcardIndex < 1 || wildcardIndex > variableStringMatchers.size()) {
                throw new IllegalArgumentException("Invalid reference to wildcard (" + wildcardIndex
                    + ", must lie between 1 and " + variableStringMatchers.size() + ")");
            }

            return wildcardIndex;
        } catch (NumberFormatException e) {
            return 0;
        }
    }

    /**
     * Adds the given variable string matcher to the list of string matchers.
     */
    private VariableStringMatcher rememberVariableStringMatcher(VariableStringMatcher variableStringMatcher) {
        if (variableStringMatchers != null) {
            variableStringMatchers.add(variableStringMatcher);
        }

        return variableStringMatcher;
    }

    /**
     * Retrieves the specified variable string matcher from the list of string matchers.
     */
    private VariableStringMatcher retrieveVariableStringMatcher(int index) {
        return (VariableStringMatcher)variableStringMatchers.get(index);
    }

    /**
     * A main method for testing name matching.
     */
    public static void main(String[] args) {
        try {
            System.out.println("Regular expression [" + args[0] + "]");
            NameParser parser = new NameParser();
            StringMatcher matcher = parser.parse(args[0]);
            for (int index = 1; index < args.length; index++) {
                String string = args[index];
                System.out.print("String             [" + string + "]");
                System.out.println(" -> match = " + matcher.matches(args[index]));
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}
